effort or efforts?

[jayan12]

1. Thank you Ravi and Sundar for your effort which you make for helping people.
2. Thank you Ravi and Sundar for your efforts which you make for helping people.

which one is correct?

[Frank Antonson]

Both are correct.
It depends upon what you are trying to say.
Linguist Farmer

[kfredson]

1. Thank you Ravi and Sundar for your effort which you make for helping people.
2. Thank you Ravi and Sundar for your efforts which you make for helping people.

which one is correct?

Neither is incorrect but I would rephrase them as follows:

Thank you, Ravi and Sundar, for the effort(s) that you put into helping others.

You could also drop out "that" (our "which").