The correct answer is Portuguese, which has the largest number of speakers among the options given.

Let`s go through each option:

1. Bengali is spoken widely in Bangladesh and in India but its number of speakers is less compared to Portuguese.

2. French, although spoken in many countries as an official language, doesn`t match up to the number of Portuguese speakers.

3. Japanese is predominantly spoken in Japan only, hence it does not have as many speakers globally.

4. Portuguese, the correct answer, is spoken by a large population in Portugal, Brazil, and several other places around the world, making it the language with the largest number of speakers among these choices.

It`s crucial to note that these numbers can change over time due to various socio-political changes influencing the number of speakers around the globe.