The correct answer is: D. many
The word “many” is the most appropriate word to complete the sentence “Have . . . . . . love for animals.” This is because “many” refers to a large number of things, which is consistent with the idea that people who love animals often have a deep and abiding affection for them.
The other options are not as appropriate. “Lots of” is similar to “many,” but it is slightly more informal. “A little” and “a few” are both too small to accurately describe the amount of love that people have for animals.
In addition, “many” is the most concise and easy-to-understand word of the four options. This makes it the best choice for completing the sentence.