Many environmentalists, and some economists, say that free

[Toponepercent GMAT]

Many environmentalists, and some economists, say that free trade encourages industry to relocate to countries with ineffective or poorly enforced antipollution laws, mostly in the developing world, and that, in order to maintain competitiveness, rich nations have joined this downward slide toward more lax attitudes about pollution.
A. that, in order to maintain competitiveness, rich nations have joined this downward slide toward more lax attitudes about pollution
B. that, to maintain competitiveness, rich nations join this downward slide toward more lax attitudes about pollution
C. that rich nations join this downward slide toward more lax attitudes about pollution because they want to maintain competitiveness
D. that rich nations joining this downward slide toward more lax attitudes about pollution is a result of wanting to maintain competition
E. that wanting to maintain competition is making rich nations join in this downward slide toward an attitude about pollution that is more lax

[GMATGuruNY]

When posting an SC, please underline the relevant portion.

Many environmentalists, and some economists, say that free trade encourages industry to relocate to countries with ineffective or poorly enforced antipollution laws, mostly in the developing world, and that, in order to maintain competitiveness, rich nations have joined this downward slide toward more lax attitudes about pollution.

A. that, in order to maintain competitiveness, rich nations have joined this downward slide toward more lax attitudes about pollution

B. that, to maintain competitiveness, rich nations join this downward slide toward more lax attitudes about pollution

C. that rich nations join this downward slide toward more lax attitudes about pollution because they want to maintain competitiveness

D. that rich nations joining this downward slide toward more lax attitudes about pollution is a result of wanting to maintain competition

E. that wanting to maintain competition is making rich nations join in this downward slide toward an attitude about pollution that is more lax

The purpose of the simple present tense is to express a GENERAL TRUTH: an action that does not happen at a particular moment but that is generally true.
B and C: Many environmentalists say...that rich nations join in this downward slide.
Here, THIS downward slide implies not a general truth but a CURRENT EVENT: a slide that is happening NOW.
Since the action in B and C is not a general truth but a current event, the usage of join (simple present tense) is inappropriate.
Eliminate B and C.

D: rich nations...is a result
Here, is (singular) does not agree with rich nations (plural).
Eliminate D.

E: pollution that is more lax
Here, the portion in red seems to refer to pollution, implying that POLLUTION is MORE LAX.
Not the intended meaning.
The intended meaning is that ATTITUDES are more lax.
Eliminate E.

The correct answer is A.