Let's look at the options one after the other with a view to picking the most correct in meaning to the question.
In Option A - INCORRECT.
It seeks to explain that there were more implementation in 1973 than as of now. Nevertheless, the manner it was arranged without any difference from the question underlined does not allow any body to understand why it would be a copied answer.
In Option B - INCORRECT.
Here, there seems to be an argument against ''than'' which means in comparison, one is greater. The use of ''as'' could qualify as though it's a direct replacement word which does not show which is prominent than the other.
In Option C - INCORRECT
The concept of answering the questions should be hinged on repetition of the question itself with mere and light charges to some words. This option is a bit correct but it offers no or little linguistic construction difference.
In Option D - CORRECT.
This is appropriate enough for consideration. It seeks to explain that ''consequently'' the program has now taken a different dimension ''than it did'' back in the year being compared.
In Option E - INCORRECT.
This has given the statement a different meaning although there are still elements of similarities. The sentence could have been better arranged to suit the purpose more. Clearly not what we need.