Read the text and determine if the sentence is true (see options at the end):

A variety of devices could be powered selectively from a single-power source carried on the body via multiple power supply signals at different frequencies, according to the patent abstract.

Sentence: According to the patent abstract, there were multiple power supply handwritten signatures at different frequencies.
Choices:
[a]. Yes;
[b]. It's impossible to say;
[c]. No;