The given number series is: 24, 60, 120, 210,?

To find the missing term, we need to identify the pattern followed in the series. Let's look at the difference between consecutive terms:

60 - 24 = 36
120 - 60 = 60
210 - 120 = 90

We can see that the difference between consecutive terms is increasing by 24, 36, and 30 respectively. This means that the next term should be:

210 + 120 = 330
330 + 150 = 480
480 + 180 = 660
660 + 210 = 870

However, none of these options are given in the answer choices. So, let's try another approach by looking at the products of consecutive terms:

24 x 2.5 = 60
60 x 2 = 120
120 x 1.75 = 210

We can see that each term is obtained by multiplying the previous term by a decreasing factor of 2.5, 2, and 1.75 respectively. So, the next term should be:

210 x 1.5 = 315
315 x 1.75 = 551.25

Again, neither of these options is given in the answer choices. So, let's try one more approach by looking at the differences between the products of consecutive terms:

60 - 24 = 36
120 - 60 = 60
210 - 120 = 90

We can see that the differences are increasing by 24, 36, and 30 respectively. This suggests that the next difference should be:

90 + 24 = 114

So, the next term should be:

210 + 114 = 324

This option is closest to one of the answer choices, which is 336. However, we can see that the actual next term is slightly lower than 336. This could be due to rounding errors or differences in the pattern we identified. Nonetheless, the closest answer choice is option 'B' which is 336.