Answer:
![\boxed {\boxed {\sf D. \ 4}}](https://img.qammunity.org/2021/formulas/chemistry/high-school/mschpjihx56jo7c43xzpa1sqchcaird8x1.png)
Step-by-step explanation:
The neutrons in an element can be found by subtracting the atomic number from the atomic mass.
![\sf N=atomic \ mass- atomic \ number](https://img.qammunity.org/2021/formulas/chemistry/high-school/7u1ms9qprse9zjg5sm9n6l3d6org8yhmqf.png)
Li is the symbol for lithium.
This element has an atomic mass of 6.941, which we can round to 7.
Lithium's atomic number is 3.
![\sf atomic \ mass =7 \\atomic \ number =3](https://img.qammunity.org/2021/formulas/chemistry/high-school/oxm2mdhefagnq44plvrw4plutncpx9nhvf.png)
![\sf N=7-3](https://img.qammunity.org/2021/formulas/chemistry/high-school/pzshuh6geb1tjqbxp5uxv7mikhdo3vv4wi.png)
![\sf N= 4](https://img.qammunity.org/2021/formulas/chemistry/high-school/d68alg50wj87m128o02atp60c2f79x4hg8.png)
Lithium has a total number of 4 neutrons.