It is a strengethen question. It is asking you find an unstated premise in support of the conclusion.

sankruth is correct. Any assumption question is a strengthen question because assumptions are simply unstated premises so they support the argument in unstated ways.

I agree with sankruth
Assumption question is a strengthen question.An assumption is something that the author's conclusion depends upon.It is a connection between the stated premises and the conclusion.

I would not assume the that strengthen question is same as assumption question. This is explanation from LSAT bible...

Strengthen questions ask you to support the argument in any way
possible. This type of answer has great range, as the additional support
provided by the answer choice could be relatively minor or major.
Speaking in numerical terms, any answer choice that strengthens the
argument, whether by 1% or by 100%, is correct.

Assumption questions ask you to identify a statement that the argument
assumes or supposes. An assumption is simply an unstated premise—
what must be true in order for the argument to be true. An assumption
can therefore be defined as what is necessary for the argument to be
true.

For example.
"An argument concludes that a teenager is an outstanding golfer."

In a Strengthen question, the correct answer could be: “The teenager
won a local club tournament.” This answer choice supports the idea
that the teenager is an outstanding golfer, but does not undeniably
prove the teenager to be outstanding (what if the tournament was
composed primarily of pre-teen players?) nor is the answer an
assumption of the conclusion.

In an Assumption question, the correct answer could be: “The teenager
always hits the ball” or “The teenager never swings and misses the
ball.” Either statement is an assumption of the argument; otherwise
how could the teenager be an outstanding golfer?