According to Ohm's Law, the current I circulating through a resistor with resistance R connected to a voltage V is given by:
When an array of resistors is connected in parallel, the voltage through each of them is the same. Then, for a fixed voltage, the current will be greater if the resistance is smaller. We can conclude this from the fact that R appears in the denominator of the expresion: If R grows, the quotient becomes smaller. Similarly, a smaller value of R will result in a greater value for the quotient V/R.
Then, the highest current will flow through the resistor with the smaller resistance. Since R1
Therefore, R1 has the highest current.