diff --git a/rtchallenge/examples/eoc7.rs b/rtchallenge/examples/eoc7.rs
index 726857c..959b005 100644
--- a/rtchallenge/examples/eoc7.rs
+++ b/rtchallenge/examples/eoc7.rs
@@ -1,9 +1,10 @@
 use std::{f32::consts::PI, time::Instant};
 
 use anyhow::Result;
+use structopt::StructOpt;
 
 use rtchallenge::{
-    camera::Camera,
+    camera::{Camera, RenderStrategy},
     lights::PointLight,
     materials::Material,
     matrices::Matrix4x4,
@@ -14,8 +15,17 @@ use rtchallenge::{
     WHITE,
 };
 
+/// End of chapter 7 challenge.
+#[derive(StructOpt, Debug)]
+#[structopt(name = "eoc7")]
+struct Opt {
+    #[structopt(long, default_value = "rayon")]
+    render_strategy: RenderStrategy,
+}
+
 fn main() -> Result<()> {
     let start = Instant::now();
+    let opt = Opt::from_args();
     let width = 1024;
     let height = 1024;
     let light_position = Tuple::point(-10., 10., -10.);
@@ -26,6 +36,7 @@ fn main() -> Result<()> {
     let to = Tuple::point(0., 1., 0.);
     let up = Tuple::point(0., 1., 0.);
     camera.set_transform(view_transform(from, to, up));
+    camera.render_strategy = opt.render_strategy;
 
     let mut floor = Sphere::default();
     floor.set_transform(Matrix4x4::scaling(10., 0.01, 10.));